Abstract: The present article reviews the structure of hair and various types of hair damage, demonstrating that repair treatments must intervene at several levels within hair. While film-forming agents are often used, they slow or prevent the penetration of actives. A hair serum including natural actives and omitting these film-formers was thus formulated and tested for its repair capabilities.

The number of consumers with damaged hair continues to rise due to external factors; for example, mechanical damage from brushing, hair-straightening irons, etc.; chemical treatments such as hair dyeing and bleaching; and environmental damage from the sun, pollution, etc. Once hair is damaged, repair treatments must intervene on several levels to repair it—from the middle of the cortex to the cuticle. However, film-forming agents such as silicones, which are commonly used, cover the hair with a fine waterproof layer, slowing or even preventing the penetration of actives to repair hair. The present article therefore explores the development of a repair serum based on natural actives and omitting such film-formers.